December 13, 2006—To paraphrase a killer-rabbit-afflicted enchanter in Monty Python and the Holy Grail, that's no ordinary squirrel. "He's got huge, sharp er. He can leap about. Look at the bones!"

Looking at the bones is exactly what paleontologist Jin Meng, of New York City's American Museum of Natural History, did. Fossils from eastern Mongolia told him and colleagues they'd discovered a completely new order of mammals.

Volaticotherium antiquus—"ancient gliding beast"—is what they named the only known species of the new order (shown above in an artist's conception released today by the journal Nature, along with Meng and company's study).

Weighing in at less than a pound (half a kilogram), the squirrel-like creature boasted beastly teeth that give it away as an insect-eater, like most mammals of its time, according to the study.

More important, though, are fossil impressions of an airfoil-like skin-membrane fold—as well as elongated limbs needed to support such a "sail"—which identify the animal as a glider, the researchers say. And its backbones suggest it had a long tail that served as a stabilizing rudder.

The team says it all adds up to a mammal that glided 70 million years before any other—and possibly even before birds took to the air.

Now that's something completely different.

—Ted Chamberlain

Editor's Note: Jin Meng has received research funding from the National Geographic Society's Committee for Research and Exploration.